Patent Application
20140092365
The present invention relates to a space image forming element for displaying an image in the air by, using reflection of light by two mirror-face elements which are arranged in an array and are orthogonal to each other, forming an image of reflection light in a position which is plane-symmetrical to a light source, and a method of manufacturing the same. The invention further relates to a display device and a terminal using a space image forming element manufactured by the method of manufacturing the space image forming element.
3D display devices are used as display devices of various information processing terminals such as a TV, a portable terminal, and a portable game device. Recently, a liquid crystal display device capable of displaying a glasses-free 3D image is in practical use.
There is a case that the user comes to have eyestrain due to long-time viewing in those 3D display devices using binocular parallax, and a 3D display system having less burden on viewers is being demanded.
To address the demand, in patent literature 1, 2, and 3 listed below, there is proposed a system for displaying an image in the air, as illustrated in
In a 3D display system using binocular parallax, an object to be visually recognized is a virtual image. On the other hand, a 3D display image by the two-face-corner reflector array is a real image, so that feeling of fatigue of the eyes and brain is reduced.
Examples of a space image forming element used in the system include a configuration that a plurality of rectangular holes penetrating in the thickness direction are formed in a predetermined base and inner walls of each of the holes are formed by mirror faces which are orthogonal to each other, and a configuration that side wall faces of a transparent structure formed on a light transmission substrate are formed by mirror faces.
To obtain a bright image by increasing the brightness of reflection light, high reflectance needs to be realized. To realize high reflectance, it is effective to increase the aperture ratio determined by the ratio of the through holes in a base face, the transparent structure, or the like. For this purpose, the distance of neighboring through holes or transparent structures needs to be made shorter.
However, as illustrated in
In addition, since miniaturization of the through holes 7 by processing is limited, the aperture ratio determined by the ratio of the through holes 7 in the plane of the base 6 also becomes low and, as a result, a problem such that reflectance also becomes low occurs.
The configuration that the side wall faces of the transparent structure formed on the light transmission substrate are formed by mirror faces has a problem such that the incident angle of light is limited in order to assure high reflectance in a state where the side wall faces are transparent.
As illustrated in
An object of the present invention is, therefore, to provide a space image forming element realizing higher reflectance and larger area by making aperture ratio and transmittance higher and a method of manufacturing the same, thereby realizing high reflectance and formation, in the air, of an image having high brightness obtained as a result of the high reflectance.
To solve the problems, a method of manufacturing a space image forming element of the present invention includes: a step of forming a transparent photosensitive resin on a transparent substrate on which a first conductor is formed; a step of forming a light transmission region made by patterning the transparent photosensitive resin, on the transparent substrate other than a place where the first conductor is formed, by ultraviolet light irradiation to a face opposite to the transparent substrate face obtained by forming the transparent photosensitive resin and a subsequent developing process; and a step of forming a second conductor on the first conductor and between light transmission region patterns by electroplating using the first conductor as a cathode.
In the method of manufacturing a space image forming element of the present invention, the first conductor has shielding property from ultraviolet rays.
In the method of manufacturing a space image forming element of the present invention, the first conductor is made of a metal, and the metal is nickel, aluminum, chromium, or an alloy whose main component is any of the metals.
In the method of manufacturing a space image forming element of the present invention, the second conductor is a metal, and the metal is nickel, nickel palladium, or nickel cobalt.
Further, in the method of manufacturing a space image forming element of the present invention, a cover layer is disposed on the surface of the light transmission region and the second conductor, and the surface of the cover layer has a flat shape.
The cover layer in the space image forming element is made of a transparent resin having the same refractive index as that of the light transmission region.
A space image forming element of the present invention is manufactured by the above-described manufacturing method.
In the present invention, a transparent photosensitive resin is formed on a transparent substrate on which a first conductor is formed. By ultraviolet light irradiation to a face opposite to the transparent substrate face obtained by forming the transparent photosensitive resin and a subsequent developing process, it is possible to form a light transmission region disposed on a first conductor, which is disposed on the surface of the transparent substrate and has a predetermined plane pattern shape, and a region in which the first conductor is not formed.
Although a pattern having high aperture ratio cannot be conventionally formed because of mechanical process, a fine pattern can be formed by using photolithography process as in the present invention.
Further, by electroplating using the first conductor as a cathode and forming the second conductor on the first conductor and between the light transmission region patterns, a structure that the light transmission region, the first conductor, and the second conductor disposed on the surface of the first conductor are disposed in an array shape on the surface of the transparent substrate can be obtained.
Since a precise film can be formed in a fine pattern in the present invention as described above, the interface between the light transmission region and the second conductor becomes a mirror face having high reflectance. In addition, a precise metal layer can be formed to a transparent photosensitive resin having high aspect ratio.
Consequently, a high-reflectance space image forming element can be realized. Using the space image forming element described above allows formation of an image having high brightness in the air can be realized.
As described above, according to the present invention, finer pattern, higher aperture ratio of the light transmission region, higher transmittance, and larger area can be simultaneously realized, and higher reflectance and formation of an image having high brightness in the air obtained as a result of the higher reflectance can be realized.
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
A space image forming element of the embodiment has a transparent substrate 1. The transparent substrate 1 is made of glass or a resin such as PET (polyethylene terephthalate) or PC (polycarbonate).
In the same plane on the transparent substrate 1, transparent layers 2 disposed in a matrix and a pattern-shaped metal layer 20 partitioning the transparent layers 2 are provided. The metal layer 20 comprises two layers of a first metal layer 3 and a second metal layer 4.
As a proper shape, the transparent layer 2 has a height (thickness) which is properly in the range of 10 μm to 100 μm and is 40 μm in the first embodiment. The width of the transparent layer 2 is properly in the range of 10 μm to 100 μm in the surface of the transparent substrate 1 and is set to 40 μm in the first embodiment.
The width of the metal layer 20 is properly in the range of 1 μm to 30 μm in the surface of the transparent substrate 1 and is set to 10 μm in the first embodiment.
As will be described later, the first metal layer 3 has both the function of a photo mask for forming the transparent layer 2 and the function of an electrode at the time of forming the second metal layer 4 by electroplating. Consequently, shielding property from ultraviolet light as exposure light and conducting property to function as an electrode for electroplating are necessary. To assure adhesion strength of the second metal layer 4, the electrode for electroplating is preferably made of metal.
Although a conductive resin or the like may be used as a material having the conducting property, to assure sufficient strength of adhesion to the second metal layer 4 and to provide a mirror face having high reflectance in an interface with a transparent pattern side wall, a conductive metal needs to be used.
In the example of
First, the pattern of the first metal layer 3 is formed on the surface of the transparent substrate 1 (refer to
The first metal layer 3 is made of chromium, aluminum or nickel as a metal having both shielding property and conducting property, an alloy whose main component is any of the metals, or the like. The width of the first metal layer 3 is properly in the range of 1 μm to 30 μm in the surface of the transparent substrate 1 and is set to 10 μm in the embodiment.
The film thickness of the second metal layer 4 is properly in the range of 0.1 μm to 0.4 μm and is set to 0.2 μm in the embodiment. Subsequently, a transparent photosensitive resin 25 is formed on the surface of the transparent substrate 1 (refer to
The transparent photosensitive resin 25 is a negative resist of an epoxy base (concretely, glycidyl ether derivative of bisphenol A novolac) which is irradiated with ultraviolet light so that acid is produced by a photo initiator and which polymerizes curable monomer using the protonic acid as a catalyst. The transparent photosensitive resin 25 has a characteristic of very high transparency in a visual light range.
Since the molecule weight before curing of the curable monomer contained in the transparent photosensitive resin 25 is relatively small, the curable monomer is dissolved very easily in a solvent such as cyclopentanone, PEGMEA (propylene glycol methyl ether acetate), GBL (gamma butyl lactone), or MIBK (methyl isobutyl ketone), so that a thick film can be easily formed.
Further, the transparent photosensitive resin 25 has high light transmission also at wavelengths in the near-ultraviolet range, and therefore, has a characteristic that it transmits ultraviolet rays even the film made thereof is thick.
As a method of forming the transparent photosensitive resin 25, for example, a film forming method such as a slit die coater, a wire coater, an applicator, dry film transfer, a spray coating, or the like can be used.
Since the transparent photosensitive resin 25 has such a characteristic, a pattern having high aspect ratio which is three or higher can be also formed. Further, a number of functional groups exist in the curable monomer, so that, after curing, the transparent photosensitive resin 25 becomes a cross-link having very high density and has a characteristic that it is thermally and chemically highly stable. Consequently, the transparent photosensitive resin 25 is easily processed after pattern formation.
Obviously, the transparent photosensitive resin 25 used in the present invention is not limited to the above-described transparent photosensitive resin (trade name: SU-8). Any light curing material may be used as long as it has similar characteristics.
Subsequently, the pattern of the first metal layer 3 is used as a mask for exposure and the back side of the transparent photosensitive resin 25, which is the face opposite to the face on which the resin of the transparent substrate 1 is formed, is exposed to light (refer to
A UV light source is used as the light source, and UV light having a wavelength of 365 nm is emitted as exposure rays 30. The exposure amount in this case lies in the range of 50 mJ/cm2 to 500 mJ/cm2 and is set to 300 mJ/cm2 in the embodiment. By performing exposure and development, the transparent layer 2 is formed (refer to
As the shape of the transparent layer 2, the height (thickness) is properly in the range of 10 μm to 100 μm and is set to 40 μm in the first embodiment. The width of the transparent layer 2 is properly in the range of 10 μm to 100 μm and is set to 40 μm in the first embodiment.
Subsequently, by electroplating to an anode A using the first metal layer 3 as a cathode, the second metal layer 4 is formed on the first metal layer 3. The second metal layer 4 is made of nickel (Ni), nickel palladium (NiPd), nickel cobalt (NiCo), or the like and, in the embodiment, is made of nickel (refer to
A cover layer 15 is disposed on the transparent layers 2 and the second metal layers 4 formed on the transparent substrate 1 in a manner similar to the first embodiment. The thickness of the cover layer 15 is 5 μm to 30 μm and is set to 10 μm in the embodiment. To prevent scattering of light in the surface of the cover layer 15, surface roughness is set to 2 μm or less and is set to 1 μm in the embodiment.
As the cover layer 15, the transparent photosensitive resin 25 (trade name: SU-8) manufactured by MicroChem Corp. which is the same as that of the transparent layer 2 is used. The refractive index of the transparent photosensitive resin (trade name: SU-8) is 1.58, and the refractive index of the transparent layer 2 and that of the cover layer 15 are the same. By making the transparent layer 2 and the cover layer 15 of the same material, light is not reflected in the interface of the layers, so that deterioration in the transmittance is prevented. Obviously, the cover layer 15 used in the present invention is not limited to the transparent photosensitive resin (trade name: SU-8) but any material may be used as long as it has similar optical characteristics (refractive index, transmittance, and the like). The resin curing means is not limited to light curing resin but may be thermal curing resin.
As the method of forming the cover layer 15, for example, a film forming method such as a slit die coater, a wire coater, an applicator, dry film transfer, or spray coating may be used.
As illustrated in
By making a projection image from the light source 45 reflected twice in total, by each of two light reflection faces of the space image forming element 5, an image 55 formed in a plane-symmetrical position using the space image forming element 5 as a symmetrical plane can be obtained.
An image 55 formed by making the projected image from the display 50 reflected by the light reflection area of the space image forming element 5 is obtained on the outside of the casing 60. From the position of an observer 70, the image 55 formed on the outside of the casing 60 is seen.
The transparent layer 2 and the first metal layer 3 formed on the transparent substrate 1 in a manner similar to the first embodiment are disposed (refer to
As the transparent adhesive layer 17, the transparent photosensitive resin (trade name: SU-8) manufactured by MicroChem Corp. which is the same as that of the transparent layer 2 is used. The refractive index of the transparent photosensitive resin (trade name: SU-8) is 1.58, and the refractive index of the transparent layer 2 and that of the transparent adhesive layer 17 are the same. By making the transparent layer 2 and the transparent adhesive layer 17 of the same material, light is not reflected in the interface of the layers, so that the transmittance is held. Obviously, the transparent adhesive layer 17 used in the present invention is not limited to the transparent photosensitive resin (trade name: SU-8) but any material may be used as long as it has similar refractive index. In curing of the resin performed in FIG. 12(4), the curing means is not limited to light curing but may be thermal curing.
As the method of forming the transparent adhesive layer 17, for example, a film forming method such as a slit die coater, a wire coater, an applicator, dry film transfer, or spray coating may be used.
Next, a second structure 18 having the same configuration as that of the first structure 16 is manufactured, and another structure 18 is disposed on the transparent adhesive layer 17 so that the first and second structures 16 and 18 are deviated from each other by 90 degrees (refer to
As illustrated in
As illustrated in
The image 55 formed by making the projection image from the display 50 reflected by the light reflection face of the space image forming element 90 is obtained on the outside of the casing 60. From the position of the observer 70, the image 55 formed on the outside of the casing 60 is seen.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-218595 | Sep 2012 | JP | national |
| 2013-163650 | Aug 2013 | JP | national |
